Tooth discoloration results from formation of chromogenic substances, and their deposition on the surface of teeth, called “stain”, and causes a serious problem of aesthetic appreciation. Staining may be attributable to the contact of teeth with bactericides, such as chlorhexidine; tannin and analogous substances contained in tea, etc; and metals such as an iron. Methods of inhibiting stain formation and suppressing stain deposition to teeth have been suggested for efficiently preventing tooth discoloration.
As a method of inhibiting stain formation, Japanese Unexamined Patent Publication No. 1989-125315 discloses inhibiting stain occurrence due to tannin-based substances by polystyrene sulfonate; Japanese Unexamined Patent Publication No. 1990-56413 discloses inhibiting stain formation by blocking nonenzymatic browning reactions. However, these methods target solely a specific stain and thus are not effective against all stain types. Japanese Unexamined Patent Publication No. 1998-17443 discloses employing a sulfosuccinate surfactant for oral compositions as a stain-formation-inhibitor. For methods of suppressing stain deposition, Japanese Unexamined Patent Publication Nos. 1990-200618, 1990-209805 and 1990-223512 disclose suppressing stain deposition by coating a tooth surface with aminoalkyl silicone and Japanese Unexamined Patent Publication Nos. 1991-38517 and 1993-163126 disclose employing fluoroalkyl phosphoric acid esters to attain the same effect. However, these references disclose methods of either inhibiting stain formation or suppressing stain deposition. There have been no findings about oral compositions which can both inhibit stain formation and suppress stain deposition.
An object of the present invention is to provide an oral composition which is endowed with effects of inhibiting stain formation and suppressing stain deposition, and thereby effectively prevents tooth discoloration.